Fushan Experimental Forest (FEF) is a subtropical headwater catchment with nearly no landuse in Northern Taiwan. Meanwhile, FEF is a LTER site and a famous research site worldwide, since it attended LTER in 1993. Over the past two decades, FEF is selected as study site by many research projects and studies and thus the basic information of FEF are comprehensive. A long-term monitoring site is constructed in FEF from 2021 with sampling including rain water, through flow, soil water, groundwater and river water. In addition to basic physical parameters (rainfall, precipitation, runoff), measurement of total dissolved carbon and nitrogen, hydrogen/oxygen isotopes are also included in this site.